Jet pump



Feb.l 7, 1939.

JET PUMP Filed April 25. 1938 l F. w. wALcH 2,146,100

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sm/ ,77 A K V /74 3 ,.'Z-zvevo? W@ a federica: kfw/@262: 7 y y @MQW m Patented Feb. 7, 1939 PATENT yOFFICE JET PUMP Frederick W. Walch, Newton Center, Mass., assignor to Manning, Maxwell & Moore, Incorporated, New York, N. Y., a corporation of New Jersey Application April 25, 1938, Serial No. 204,023

14 Claims.

This invention pertains to steam pumps of the jet type, for example, inspirators or injectors, and relates more especially to a forcer tube structure for such a pump. The patents to Walsh No.

5 2,034,674, dated March 3, 1936, and No. 2,046,887, kdated July 7, 1936, describe highly desirable forms of forcer tube. As disclosed in said patents, the forcer tube comprises a receiving or combining section and a discharge or delivery section, said 10 sections collectively dening a substantially straight convergent-divergent bore or passage devvoid of lateral outlets from one end to the other, the sections being provided with complemental parts for securing them rigidly together at their l5 smaller ends and with means for removably supporting the forcer tube in the casing.

As pointed out in said patents, one of the principal diflculties encountered in the manufacture Y of pumps of this class is that of providing a :zo forcer tube which will effectively resist the powerful erosive action of the Water and entrained fsteam, such erosive action usually first showing itself at the region of the tube where the bore of the tube begins to increase in diameter, although '25 eventually appearing wherever there is a marked change in the taper of the tube. Various expedients have been tried in the effort to increase the resistance of the tube to erosion and thereby to prolong its useful life; for example, by the use of :3o a hard, wear-resistant lining at that part or parts of the tube where wear most frequently appears. Among the materials capable of resisting the peculiar wearV conditions existing in such a tube structure, stainless steel seems to be one of the :35 best, but stainless steel is hard and very difcult to machine.

If the wear-resistant sleeve be conned to that part of the tube at which the tube normally rst begins to increase in diameter, the tube structure .i may resist wear at this point so long that the first wear `will eventually appear at some other and unprotected point. It has been proposed to eX- tend the wear-resistant sleeve or lining throughout a very substantial portion of the tube, for

.115 example throughout the entire length of the delivery section, or of the combining section, but to make and properly install such a long wear-re sistant lining is troublesome and expensive. Accordingly it has been suggested that the entire 5,0 tube structure, or at least the entire combining or the entire delivery tube section, might be made rWholly oi the wear-resistant material. However, as already noted, stainless steel and materials of similar characteristics are hard, brittle and Very 55 difficult to'machine, and to make an entire tube (Cl. 10S- 277) section and properly to connect it with a complemental tube section in such a way as to ensure accurate alignment; the avoidance of leaks; and adequate resistance to breakage when the parts are subjected to prolonged and violent vibration, 5 present a mechanical problem which has not heretofore been successfully solved.

In particular it has been noted that when the delivery section is made of hard metal and screwed into a threaded socket in the end of the combining tube section, the longitudinal stress set up in the threaded portion of the delivery section, when the parts are screwed up rmlyenough to provide a leak-tight joint, so weakens the metal that the constant vibration to which the unsupported forward end of the delivery tube is subjected during use soon causes the delivery tube section to crack at its junction with the combining tube.

A principal object of the present invention is to provide a forcer tube in which a very substantial portion of the length of the bore of the tube has a surface of hard wear-resistant material. For instance, the entire delivery section may be made of this material but with provision for souniting the parts of the tube as to minimize the effect of vibration as well as to provide a leakproof joint, all in a practical and commercially feasible construction.

A further object is to provide a forcer tube in which the wall of the throat portion, as well as the walls of the combining and delivery portions for substantial distances at opposite sides of the throat, are of wear-resistant material and continuous, that is to say, these several portions of the bore are formed in a single integral piece of wear-resistant metal.

A further object is to provide a forcer tube wherein the major portion of the length of the wall of the bore is of hard wearresistant material, although that portion of the tube which en- 4o gages the injector casing thereby to support the tube as a whole in operative position, is of a soft or at least readily workable material.

A further object is to provide means whereby a hard wear-resistant tube section or member may be securely connected in leakproof relation to the other tube section or part with a minimum amount of machining of the hard section or member. Other and further advantages of the invention will be made manifest in the following more 5o detailed description and by reference to the accompanying drawing wherein:

' Fig. 1 is a longitudinal section through a forcer ytube made in accordance with a preferred embodiment of the invention;

the wide or rear end i and the small or forward end 5, while the forward end of the delivery tube is indicated at 6 and its rear end at l.

Near its forward end the combining tube is provided with a portion 8 of somewhat greater external diameter than the body of the tube, this portion 8 having external screw threads 9 for engagement with an internally screw-threaded support forming a part of the vinjecto-r casing. The combining tube is also furnished with a peripheral flange l0 having a radial shoulder il which constitutes a stop for engagement with a part ofthe injector casing, thereby tov limit movement of the tube structure as it is screwed into place, and to provide a leakproof joint with the surface of the casing with which it engages. To facilitate the mounting of the tube structure in the casing, the combining tube section 2 may be provided with angular faces l2 or the like, designed for engagement by a wrench or other suitable tool. It is contemplated that the combining tube section 2 will be made of some material which may be worked readily, for example, bronze, so that the screw threads 9, the shoulder Il, and the wrench-engaging surfaces l2 may be formed without too lmuch diiflculty or expense.

In Fig. 5 the improved forcer tube is shown, for example, as mounted in an injector casing, the latter having a transverse septum i3 having a radial surface i4 with which the shoulder Il of the forcer tube engages when the tube is mounted in position. A septum I3 separates the. inlet chamber l5 of the casing from the outlet chamber I6. As illustrated, the casing comprises separable parts l1 and lla, united by bolts Hb, but the particular style ofcasing employed is immaterial so long as it is provided with an internally screw-threaded support having a stop surface with which the shoulder Il may engage.

The smaller or forward end k5 of the combining tube is furnished with a substantially cylindrical bore IS which provides an elongate'socket for the reception of the rear end of the delivery tube section 3. This socket terminates atan abrupt radial shoulder 2t which constitutesa stop for the inner end of the delivery tube section, the latter being substantially cylindrical and itting snugly within the socket I9. Adjacent-toA its inner orrear end the outer surface Vof the delivery tube section 3 is furnished with screw threads 22 Awhich engage screw threads in the wall of the socket at the inner end of the latter, thereby to .securethe delivery tubeto the combining tube.

Preferably the socket is of a depth of the order of one-halfthe entire length of the delivery tube and when the delivery tube is mounted in the socket with-its rear end `engaging thev shoulder 2B, the forwardly extending portion of the combining tube, beyond the screw threads 22, constitutes a supporting sleeve for the delivery tube section which prevents any possibility of breakage of the delivery tube adjacentf'torits screwthreaded portion. In this connection it may be noted that the smooth cylindrical Youter surface Y of this convergent of the delivery tube is designed to fit with a very snug fit into the long lunthreaded portion of the socket so as to eliminate any possibility of relative transverse movement of the tube within the socket. Thus any stresses which may be set up in the delivery tube in forming the threads 22 or in screwing it into the combining tube will not be harmfully increased by vibration to which the tube structure may be subjected, and any tendency for the delivery tube to crack oit near its i 'inner end is avoided.

I In accordance with the present invention it is proposed to make the entire delivery tube sectionl 3 of some very hard wear-resistant material such as stainless steel, but-as above noted, attempts Vto use such a material, which is quite brittle, have heretofore met with little success by reason of the tendency of the hard tube to break 01T at its con'- nection with the combining tube. The present invention, by providing thedelivery tube with a long tight-litting supporting sleeve, avoids this difficulty. o f

As illustrated in Fig. 1, the 'bore of the delivery tube includes the entire divergent portion 24 of the passage through the tube structure, the cylindrical throat portion 25, and also a portion 26 of the convergent partof the passage-the remainder 2l of the convergent part being formed in the combining tube 2. Thus the most pronounced changes in direction of ilow take place within the material of the delivery tube which is hard and wear-resistant so that thelife of the tube is greatly prolonged as compared with ordinary tube structures. l f Y .Y

In Fig. 2 a modified construction is illustrated wherein the delivery'tube 3a is connected to the combining tube 2a without requiring Vthat the delivery tube be screw threaded.V In this arrangement the combining tube isV provided withv a deep socket li)2L similar to that above described, but the socket is'even deeper, extending throughout substantially three-fourths of the length of the combining tube and terminating at the shoulder 20a. 24a of the passage which is divergent, the cylindrical throat portion 25a and a portion 26a of the convergent part of the passage. However, the

The delivery tube 3ab includes that portion,

delivery tube does not extend tothe bottom of 28 also of-wear-resistant material. -This sleeve provides a second passage 29 of the convergent portion of the passage, while the remainder 21a portion is in the combining tube section itself. By this arrangement the wear-resistant material is extended even further than in the arrangement of Fig..1, but by the use of the separate sleeve or liner 28 the operation of providing several of the successive tapers which usually make up the convergent portion of the passage, is made somewhat easierV than though they were ally to be formed in the delivery tube section itself.

The rear or inner end of the delivery tube section (Fig. 2) has the radial face 'la which engages the forward end face of the sleeve 28, the

face, such bore' or bores being inclined inwardly and rearwardly and being internally screw threaded for the reception of set screws 3|. The inner endsV of these set screws seat in recesses 32 and provides only the divergent portion Zll of the formedv in the outer surface ofthe delivery tube. By this arrangement theA outer surface of the deliveryy tube may be made cylindrical from end to end, with the exception of these slight recesses which may be formed by grinding, for example, and which do notsubstantially weaken the structure of the delivery tube. The arrangement of the set screws is such as to force the delivery tube rearwardly and thus to form tight joints at the points la and 20a.

In the arrangement shown in Eig. 3, which is in general quite similar to that of Fig. 2, the screwthreaded bores'formed through the wall of the combining tube are radial and receive set screws 33'having conical tips 34 which engage conical recesses of somewhat larger diameter in the delivery tube section Sb, the conical tips of the set screws engaging these recesses at their rear sides so, as to force the delivery tube rearwardly.

In the arrangement shown in Fig. 4, the cornbining tube 2c has the elongate socket I9c terminating at the radial shoulder 20C, the socket being of about the same depth as that shown in Fig. 2. In this instance the delivery tube 3c is shorter than in the arrangements previously described passage and a part 25 of the throat of the passage. The remainder 25X of the throat, as Well as portions 28C and 23X of the convergentJ part of the passage, are formed in a long wear-resistant liner sleeve 28c having a radial face at its forward end against which the rear end of the delivery section abuts to make a` tight joint. In this case the joint comes at about the middle of the throat where there is no outward pressure, so that possibility of leakage at this point is eliminated. For holding the delivery tube section in place, the extreme forward end of the combining tube is reduced in diameter at 3S and externally screw threaded for the reception of a clamping sleeve 31 having an internal radial flange 38 which is designed to engage a split ring 38 setinto a peripheral groove in the delivery tube sectionc.

kSuch a groove may readily be formed even in such hard material as that of the delivery tube, and the ring 39 forms an abutment shoulder for engagement by the clamping sleeve 3'! whereby the delivery tube section and the lining section 23c `maye be firmly clamped in position within the combining tube. This arrangement, like those shown in Figs. 2 and 3, provides a forcer tube structure having a hard wear-resistant lining extending throughout the greater part of its length, although that part of the tube structure which rcarries the elements (for example parts 8, 9, ID, Il and l2) by which it is mounted in the injector casing may be of a softer and more easily workable material.

While certain desirable embodiments of the invention have been illustrated by way of example, it is to be understood that the invention is not necessarily limited to these precise embodiments or to the details disclosed, but is to be regarded as broadly inclusive of all equivalent constructions such as fall within the terms of the appended claims.

I claim.:

l. A forcer tube comprising a combining section and a unitary delivery section, said sections, When assembled, forming a continuous convergent-divergentpassage devoid of lateral outlets, the combining section being provided with means for mounting it in an injector casing, the delivery section being'of substantially uniform external diameter from end toend and being socketed for approximately one-half its length within the substance of` the' combining tube, and means removably uniting the tube sections.

2. A'forcer tube comprising a combining section and a delivery section, said sections when assembled forming a continuous convergentdivergent passage devoid of lateral outlets, the combining, section being provided with means for mounting it in an injector casing, the rear end of the delivery tube fitting snugly within an axial socket in the combining tube to a depth o1" the order of one-half the entire length of the delivery tube, and` means at the rear end portion of the delivery tube for connecting it to the combining tube section.

3. A forcer tube comprising a combining section and a unitary delivery section of a hard wear resistant material throughout, said sections, when assembled, forming a convergent-divergent passage, the combining tube section being of a material which is readily machined and being provided with means for mounting it in an injector casing, the bore of the combining tube section having an elongate substantially cylindrical portion of a length which is at least one-half the entire length of the combining tube section, said cylindrical portion of the bore constituting a socket for the reception of the rear end of the delivery tube section, said rear end of the delivery tube section being of such shape and dimensions as to nt snugly within said socket, and means removably securing the delivery tube section in associated relation with the combining tube section.

4. A forcer tube comprising a combining section and a unitary delivery section, said sections, when assembled, forming a continuous convergentdivergent passage devoid of lateral outlets, the combining section being provided with means for mounting it in an injector casing, the delivery section being of substantially uniform external diameter from end to end and being socketed for approximately one-half its length Within the substance of the combining tube, the inner end portion only of the socketbeing screw threaded, said delivery section having external screw threads adjacent to its inner end only for engagement with the screw-threaded port-ion of the s cket and having a smooth outer surface such as snugly to engage the unthreaded portion of the socket wall.

5. A forcer tube comprising a combining section and a delivery section, said sections, when assembled, forming a convergent-divergent passage, the combining tube section being provided with means for mounting it in an injector casing, the bore of the combining tube section having an elongate substantially cylindrical portion constituting a socket for the reception of the rear end of the delivery tube section, the latter section being substantially cylindrical from end to end and having its rear end portion :fitting snugly within the socket, the inner end portion only ci the socket being screw threaded and the inner portion only of the delivery tube section being screw threaded for engagement with the threaded part of the socket, the major portion of the length ofthe socket having a smooth wall and the delivery section having an unthreaded portion of substantial length which iits snugly in said smooth walled part of the socket.

6. A forcer tube comprising a combining section and a delivery section, said sections, when assembled, forming a continuous convergent-divergent passage devoid of lateral outlets, the combining section being providedwith means for mounting it in an injector casing, the bore of the combining tube section having a. substantially cylindrical portion extending from the forward end of the section for a distance of the order of at least onehalf the length of the tube toward its rear4 end, said cylindrical portion constituting a socket for the rear end of the delivery tube section, the delivery section being cylindrical and of substantially uniform external diameter from end to end and fitting snugly within said bore, means constituting a stop for klimiting movement of the delivery section into the socket, and securing means operative to exert force tending to move the delivery section into engagement with said stop means.

7. A forcer tube comprising a combining section and a delivery section, said sections when assembled forming a continuous convergent-divergent passage devoid of lateral outlets, the combining section being provided with means for mounting it in an injector casing, the rear end of the delivery tube tting snugly within an axial socket in the combining tube to the depth of the order of one-half the entire length of the delivery tube, the combining section having a screw-threaded bore of relatively small diameter leading from its outer surface into the socket, and a threaded clamping element engaging said bore, the smooth cylindrical part oi the delivery section having a recess for engagement by the inner end of said clamping element.

8. A forcer tube comprising a combining section and a delivery section, said sections, when assembled, forming a continuous convergentdivergent passage devoid of lateral outlets, the combining section being provided with means for mounting it in an injector casing, the bore of the combining section having an elongate, substantially cylindrical portion constituting a socket for the reception of the rear end of the delivery section, the latter section iitting snugly within the socket, the delivery section comprising the entire divergent portion ofthe passage and also the smaller end portion of the convergent part of the passage, the combining section having a screwthreaded bore of relatively small diameter leading from its outer surface into the socket, the axis of said bore being inclined toward the bottom of the socket, and a set screw engaging said threaded bore, the cylindrical surfaceY of the delivery section having a recess for engagement by the inner end of said set screw.

9. A forcer tube comprising a combining section and a unitary delivery sectionof a hardV wear-resistant'material throughout, said sections, when assembled, forming a convergent-divergent passage, the combining section being of a material which is readily machined and being provided with means for mounting it in an injector casing, the bore of the combining section having an elongate substantially cylindrical portion of a length which is at least one-half the entire length of the combining section, said cylindrical portion of the bore constituting a socket for the reception of the rear end ofthe delivery section, said rear end of the delivery section being of such shape and dimensions as to fit snugly within the socket, the forward end of the combining section being externally screw threaded, a threaded clamping ring engaging said threaded end portion of the combining section, and means carried by the delivery section for engagement by said clamping ring whereby rotation of the clamping ring, relauniting the combining and delivery tube sections,

the combining tube section comprising means external to the delivery tube section for supporting the delivery tube section for a substantial part of the length of the latter forwardly of the location of the connecting means.

11. A forcer tube comprising a combining section and a delivery section, said sections, when assembled, forming a continuous convergentdivergent passage devoid of lateral outlets, the combining section being `provideollwith means for mounting it in an injector casing, the delivery tube being of a wear-resistant material subject to breakage when exposed to vibration, and means connecting the inner end of the deliverytube to the combining tube, the combining tube compris- `ing rigid means which externally engages the delivery tube at a point'substantially spaced, in a forward direction, from the connecting means.l

12. A forcer tube comprising a combining section and a delivery section, said sections, when assembled, forming a continuous convergentdivergent passage devoid of lateral outlets, the combining tube section being provided with means for mounting it in an injector casing, the bore of the combining tube section having an elongate, substantially cylindrical portion, constituting a socket for the reception of the rear end of the delivery tube section, the latter section fitting snugly within the socket,ithe delivery tube section comprising the entire divergent'portion of theV passage and also the smaller end portion of the convergent part of the passage, and means,

tion and a unitary delivery section of wear-resistant material and being of substantially uniform external diameter from end to end, said sections, when assembled, forming a convergent-divergent passage, the combining tube Section being of a material which is readily machinable and being provided with means for mounting it in an injector casing, the bore of the combining tube section having an elongate substantially cylindrical portion constituting a socket for the reception of the rear end portion of the delivery tube section, the bore of the delivery tube section defining the entire divergentportion of the passage as well as the throat portion and also the smaller end of the convergent portion of the passage, Ythe major part, at least of the length ofthe delivery tube which engages the socket having a substantially smooth exterior surface which iits snugly .against the wall of the bore.

14. A forcer tube comprising a combining section and a one-piece delivery section of substantially uniform external diameter from end to end, said sections, when assembled, forming a convergent-divergent passage, the combining tube section being provided with means for mounting it in an injector casing, the bore of the combining tube section havingr an elongate substantially cylindrical portion constituting a socket for the passage, a Wear-resistant lining fitting within the reception of the rear end portion of the delivery rear end of the socket and having an axial bore tube section, the bore of the delivery tube section which provides another portion of the convergent defining the entire divergent portion of the paspart of the passage, and means for securing the sage as Well as the throat portion and also the deliveiy tube section in the socket. 5 smaller end of the convergent portion of the FREDERICK W. WALCH. 

